272 MORPHOLOGY AND EVOLUTION Apes and reduced in Man. The epididymis is long and ends in the vas deferens, which has the usual cord-like consistence. The vas runs through the spermatic cord and inguinal canal. It then dips down, and passing on the back of the bladder it unites with the duct of the corresponding seminal vesicle. After receiving the latter it may become dilated. The vesiculse seminales in the Orang and Chimpanzee are large pyriform structures touching mesially and extending beyond the bladder laterally; so they differ from the vesicles in Man, in whom they never project beyond the bladder. Each consists of a tube which is greatly convoluted and coiled, and no glandular diverticula project from it. It is impossible to extend the tube completely, for many of the coils cannot be unravelled. Pousargues found that the tube could be extended to 40 cm., but that was not the entire length, Leuckart (107) pointed out that the length of the tube is inversely proportional to the number of diverticula projecting from it. Thus the Orang has a long tube with no diverticula, but Man has a tube 10 cm. long with many glandular pockets; he has, therefore, a seminal vesicle with a short tube and a large secreting area. The prostate has the usual pyramidal form and is related to the triangular ligament, levator ani muscle and fasciae as in Man. In the Chimpanzee and Orang the prostate is entirely retro-urethral. Eetzius (135) has shown how the spermatozoa of the Gorilla resemble those of Man most closely.